System for decontaminating food articles having a porous outer surface

ABSTRACT

A method for decontaminating articles having porous outer surfaces. The method includes steps of: providing a decontamination chamber; conveying the articles through the decontamination chamber at a predetermined speed wherein the speed is selected such that the articles are disposed in the decontamination chamber for a predetermined period of time; providing a source of sterilant vapor, the source providing the sterilant vapor at a temperature within a predetermined acceptable temperature range and at a concentration within a predetermined acceptable concentration range; conveying a sterilant vapor from the source of sterilant vapor to the decontamination chamber; and exposing the articles to the sterilant vapor. The predetermined period of time and the predetermined acceptable concentration range of the sterilant vapor are selected such that the sterilant vapor does not penetrate the porous outer surfaces of the articles.

FIELD OF THE INVENTION

The present invention relates generally to the decontamination ofarticles, and more particularly, to a method and a system for supplyinga sterilant vapor to decontaminate food articles having a porous outersurface.

BACKGROUND OF THE INVENTION

As background to the present invention, current decontamination systemsfor food articles having a porous outer surface (e.g., eggs, lobsters,etc.) require placing the articles within a water bath at an elevatedtemperature and then drying the articles to remove pathogens, such assalmonella. (The terms “decontamination” and “decontaminate” will beused hereinafter to refer to processes, such as disinfection,deactivation, sanitation, sterilization, etc., that are designed to killmicroorganisms or pathogens.) If the pathogens remain on the surface ofthe article for an extended period of time (approximately two (2) hours)the pathogen may migrate through the porous outer surface of thearticle, thereby making the article a possible hazard for humanconsumption.

In addition to the foregoing, the temperature of the water bath must becarefully controlled to reduce the risk of partially cooking the foodarticles. A partially cooked food article would be undesirable to aconsumer and may pose a health risk to the consumer. In addition, waterbaths for pasteurization are prone to potential contamination build-upas eggs are continuously processed.

The present invention provides a method and a system for decontaminatingfood articles having a porous outer surface. The present inventionconveys the food articles through a decontamination chamber wherein thefood articles are exposed to a sterilant vapor at a concentrationsufficient to decontaminate the food articles and for a duration of timethat is short enough so as to avoid undesirable side effects to the foodarticles.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment of the present invention,there is provided a method for decontaminating articles having porousouter surfaces. The method includes steps of: providing adecontamination chamber; conveying the articles through thedecontamination chamber at a predetermined speed selected such that thearticles are disposed in the decontamination chamber for a predeterminedperiod of time; providing a source of sterilant vapor, the sourceproviding the sterilant vapor at a temperature within a predeterminedacceptable temperature range and at a concentration within apredetermined acceptable concentration range; conveying a sterilantvapor from the source of sterilant vapor to the decontamination chamber;and exposing the articles to the sterilant vapor. The predeterminedperiod of time and the predetermined acceptable concentration range ofthe sterilant vapor are selected such that the sterilant vapor does notpenetrate the porous outer surfaces of the articles.

In accordance with another preferred embodiment of the presentinvention, there is provided a system for decontaminating articleshaving porous outer surfaces. The system includes a decontaminationchamber. A conveyor conveys the articles through the decontaminationchamber. A source of sterilant vapor is provided. Conveying meansconveys a sterilant vapor from the source of sterilant vapor to thedecontamination chamber. A controller controls the conveyor and thesource of sterilant vapor. The controller is programmed to: control thesource of sterilant vapor to maintain the sterilant vapor within apredetermined acceptable concentration range and within a predeterminedacceptable temperature range, and control the conveyor to convey thearticles through the decontamination chamber at a predetermined speedwherein the predetermined speed is selected such that the articles aredisposed in the decontamination chamber for a predetermined period oftime. The predetermined period of time and the predetermined acceptableconcentration range of the sterilant vapor are selected such that thesterilant vapor does not penetrate the porous outer surfaces of thearticles so as to contact the food within.

An advantage of the present invention is a method and a system forproviding a sterilant vapor at a sufficient concentration to quicklydecontaminate food articles.

Another advantage of the present invention is a method and a system, asdescribed above, wherein the duration of time that the food articles areexposed to the sterilant vapor is selected to hinder undesirable sideeffects to the food articles from an organoleptic perspective.

Yet another advantage of the present invention is a method and a system,as described above, wherein the duration of time that the food articlesare exposed to the sterilant vapor is selected such that the sterilantvapor does not migrate through porous outer surfaces of the foodarticles.

Still another advantage of the present invention is a method and asystem, as described above, wherein the porous surfaces of the foodarticles are decontaminated while continuously moving through anenclosed region.

Another advantage of the present invention is a method and a system, asdescribed above, wherein the food articles move slightly during thedecontamination process such that all surfaces of the food articles areexposed to the sterilant vapor.

These and other advantages will become apparent from the followingdescription of a preferred embodiment taken together with theaccompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangement ofparts, a preferred embodiment of which will be described in detail inthe specification and illustrated in the accompanying drawings whichform a part hereof, and wherein:

FIG. 1 is a drawing schematically illustrating a system fordecontaminating articles moving along a processing line, illustrating apreferred embodiment of the present invention; and

FIG. 2 is a schematic of a controller of the system shown in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings wherein the showings are for the purposeof illustrating a preferred embodiment of the invention only, and notfor the purpose of limiting the same, FIG. 1 shows a system 10 fordecontaminating articles 12 moving along a processing line of system 10.System 10 will be described with respect to decontaminating foodarticles moving along a processing line in a food packaging facility.However, it is appreciated that the present invention may findadvantageous application in other systems for supplying a sterilantvapor to a processing line having other articles moving therealong.

In general, system 10 (shown in FIG. 1) includes a conveyor 14, adecontamination chamber 30, an aeration chamber 60, a sterilant supplysystem 100 and a controller 160. Conveyor 14 represents a processingline of a facility. A motor 16 is provided for causing conveyor 14 tomove articles 12 disposed thereon in a conveyance direction “L.” In theembodiment shown, conveyor 14 includes a mesh surface for supportingarticles 12 thereon. It is contemplated that an actuator 18 may bedisposed proximate conveyor 14. In the embodiment shown, actuator 18includes an arm (not shown). Actuator 18 may include a solenoid, an airpiston or a similar device for causing movement of the arm of actuator18. A distal end of the arm of actuator 18 is positioned to engageconveyor 14, as described in detail below.

Conveyor 14 extends through decontamination chamber 30 and aerationchamber 60. Decontamination chamber 30 includes an enclosure or housing32 having an inlet end 32 a, an outlet end 32 b and defining an interiorspace or region 32 c through which articles 12 are conveyed by conveyor14 in conveyance direction “L.” A bottom of housing 32 is trough-shapedand has an outlet port 34 formed at a lower portion thereof.

Housing 32 includes spaced-apart entrance walls 36 a, 36 b and an exitwall 38. An opening 42 extends through spaced-apart entrance walls 36 a,36 b to define an inlet to interior space or region 32 c. An opening 44extends through exit wall 38 to define an outlet from interior space orregion 32 c. In the embodiment shown, spaced-apart entrance walls 36 a,36 b are disposed generally parallel to each other and are joined by anupper wall 46 a and a lower wall 46 b.

A heating unit 52 is disposed in interior space or region 32 c ofhousing 32 near inlet end 32 a of housing 32. Heating unit 52 isprovided for heating articles 12 moving through housing 32. In theembodiment shown, heater unit 52 includes two (2) units, one disposedabove conveyor 14 and another one disposed below conveyor 14. As such,heating unit 52 is designed to uniformly heat articles 12 to a desiredtemperature.

A first temperature sensor 54 is disposed above conveyor 14 at alocation on one side of heating unit 52 and a second temperature sensor56 is disposed above conveyor 14 at a location on an opposite side ofheating unit 52. In particular, first temperature sensor 54 is disposedbetween spaced-apart entrance walls 36 a, 36 b and heating unit 52. Asshown in FIG. 1, articles 12 conveyed through decontamination chamber 30in conveyance direction “L” move pass first temperature sensor 54, thenheating unit 52 and then second temperature sensor 56. As such, firsttemperature sensor 54 provides a signal indicative of the temperature ofarticles 12 prior to heating unit 52 and second temperature sensor 56provides a signal indicative of the temperature of articles 12 afterheating unit 52. In the embodiment shown, first temperature sensor 54and second temperature sensor 56 each are an infrared sensor fordetecting the temperature of articles 12 without physically contactingarticles 12.

Aeration chamber 60 includes an enclosure or housing 62 having an inletend 62 a, an outlet end 62 b and defining an interior space or region 62c through which articles 12 are conveyed by conveyor 14 in conveyancedirection “L.” A bottom of housing 62 is trough-shaped and has an outletport 64 formed at a lower portion thereof.

Housing 62 includes entrance wall 66 and spaced-apart exit walls 68 a,68 b. An opening 72 extends through entrance wall 66 to define an inletto interior space or region 62 c. An opening 74 extends throughspaced-apart exit walls 68 a, 68 b to define an outlet from interiorspace or region 62 c. In the embodiment shown, spaced-apart exit walls68 a, 68 b are disposed generally parallel to each other and are joinedby an upper wall 76 a and a lower wall 76 b.

Decontamination chamber 30 is disposed adjacent to aeration chamber 60such that exit wall 38 of housing 32 is disposed adjacent entrance wall66 of housing 62. An upper wall 82 a and a lower wall 82 b connect exitwall 38 of housing 32 to entrance wall 66 of housing 62. In theembodiment shown, openings 42, 44 of housing 32 are generally alignedwith openings 72, 74 of housing 62 such that conveyor 14 conveysarticles 12 in a substantially straight line through decontaminationchamber 30 and aeration chamber 60. It is contemplated thatdecontamination chamber 30 and aeration chamber 60 may be disposed inother configurations, e.g., circular, angled, etc., without taking fromthe present invention, so long as articles 12 are conveyed through bothdecontamination chamber 30 and aeration chamber 60.

Broadly stated, sterilant supply system 100 includes a liquid sterilantsupply unit 110, an air conditioning unit 120, a vaporizer unit 130, anaeration unit 140 and a destroyer unit 150. The foregoing units arebriefly described below. A detailed description of the foregoing unitsis provided in U.S. patent application Ser. No. 11/741,299, herebyincorporated herein by reference.

Liquid sterilant supply unit 110 conveys a liquid sterilant to vaporizerunit 130. A supply line 112 connects a reservoir assembly 114 of liquidsterilant supply unit 110 to an external supply 116 of liquid sterilant.A sterilant feed line 118 is connected at one end to reservoir assembly114 and at another end to vaporizer unit 130. Reservoir assembly 114provides continuous, uninterrupted flow of liquid sterilant to vaporizerunit 130. It is contemplated that the liquid sterilant may includesterilants, such as hydrogen peroxide or peracetic acid.

Air conditioning unit 120 conveys a clean, dry carrier gas (e.g., air)to vaporizer unit 130, aeration unit 140 and portions of housing 32 andhousing 62, as described in detail below. Air conditioning unit 120 isprovided to condition, i.e., to filter and to dry air used in vaporizerunit 130, aeration unit 140 and portions of housing 32 and housing 62.

Air conditioning unit 120 may include a filter (not shown) for removingdebris from the air passing through air conditioning unit 120. Airconditioning unit 120 may also include a desiccant (not shown) fordrying the air passing through air conditioning unit 120. An air inletconduit 122 has a first end that communicates with the environment,namely room air, and another end that is connected to air conditioningunit 120. A first air supply line 124 is connected at one end to airconditioning unit 120 and at another end to vaporizer unit 130. A secondair supply line 126 is connected at one end to air conditioning unit 120and at another end to aeration unit 140. A third supply line 128 isconnected at one end to air conditioning unit 120 and at another end tohousing 32 and housing 62. In particular, one end of third supply line128 divides into three (3) branches, i.e., a first branch 128 a, asecond branch 128 b and a third branch 128 c. First branch 128 aconnects to upper wall 46 a. Second branch 78 b connects to upper wall82 a. Third branch 128 c connects to upper wall 76 a. In this respect,first branch 128 a conveys air to the space defined between spaced-apartentrance walls 36 a, 36 b. Second branch 128 b conveys air to the spacedefined between exit wall 38 and entrance wall 66. Third branch 128 cconveys air to the space defined between spaced-apart exit walls 68 a,68 b.

Vaporizer unit 130 is connected to sterilant feed line 118 from liquidsterilant supply unit 110 and to first air supply line 124 from airconditioning unit 120. Vaporizer unit 130 may include a vaporizer (notshown) for vaporizing the liquid sterilant supplied by liquid sterilantsupply unit 110. In the embodiment wherein the sterilant is hydrogenperoxide, the vaporizer may include a hot plate or an atomizing nozzlefor vaporizing liquid hydrogen peroxide. It is contemplated that gaseoussterilants, such as NO₂ and ozone, may be used in combination with aliquid sterilant to decontaminate articles 12. It is also contemplatedthat only gaseous sterilants, such as NO₂ or ozone, may be used todecontaminate articles 12. In the embodiment wherein only a gaseoussterilant is used, the gaseous sterilant would be supplied todecontamination chamber 30 and liquid sterilant supply unit 110 andvaporizer unit 130 would not be needed.

Vaporizer unit 130 is connected to decontamination chamber 30 by conduit132. A manifold 134 is mounted to an end of conduit 132. Manifold 134 isdisposed within housing 32 of decontamination chamber 30 at a locationbelow conveyor 14. Manifold 134 includes a plurality of spaced-apartopenings or nozzles (not shown) that communicates with interior space orregion 32 c in housing 32 of decontamination chamber 30. The nozzlesform jets of pressurized sterilant vapor that spray in a generallyupward direction over articles 12 moving through decontamination chamber30. It is contemplated that manifold 134 or additional manifolds (notshown) may be disposed in other positions relative to conveyor 14 (e.g.,above or along a side of conveyor 14) for spraying sterilant vapor onarticles 12 in other directions.

Aeration unit 140 is connected to second air supply line 126 from airconditioning unit 120. Second air supply line 126 from air conditioningunit 120 supplies filtered air to aeration unit 140. Aeration unit 140may include a blower, a flow element, a pressure sensor, a temperaturesensor, a filter, and a heater. The foregoing components are describedin detail in U.S. patent application Ser. No. 11/741,299, herebyincorporated herein by reference.

An air supply conduit 142 connects aeration unit 140 to aeration chamber60. A valve (not shown) may be disposed in air supply conduit 142 tocontrol the flow of air along air supply conduit 142. A manifold 144 isconnected to an end of air supply conduit 142. Manifold 144 is disposedin housing 62 of aeration chamber 60. Manifold 144 includes a pluralityof nozzles or ports (not shown) to distribute filtered and heated airinto aeration chamber 60. In the embodiment shown, manifold 142 isdisposed above conveyor 14. Aeration unit 140 basically provides heated,filtered air to aeration chamber 60 to remove sterilant vapor fromarticles 12 on conveyor 14. It is contemplated that manifold 144 oradditional manifolds (not shown) may be disposed in other positionsrelative to conveyor 14 (e.g., below or along a side of conveyor 14) forspraying heated, filtered air on articles 12 in other directions.

An exhaust conduit 152 connects outlet port 34 of enclosure or housing32 of decontamination chamber 30 to destroyer unit 150. A second exhaustconduit 154 is connected at one end to destroyer unit 150. Another endof second exhaust conduit 154 divides into branch conduits 154 a, 154 b,154 c and 154 d. Branch conduit 154 a connects to lower wall 46 bbetween spaced-apart entrance walls 36 a, 36 b. Branch conduit 154 bconnects to lower wall 82 b between exit wall 38 and entrance wall 66.Branch conduit 154 c connects to outlet port 64 of enclosure or housing62. Branch conduit 154 d connects to lower wall 76 b betweenspaced-apart exit walls 68 a, 68 b.

An outlet conduit 156 fluidly connects destroyer unit 150 to asurrounding environment. Destroyer unit 150 includes a destroyer (notshown). The destroyer is basically a catalytic device that is operableto destroy a sterilant vapor flowing therethrough. In the embodimentwherein sterilant vapor is hydrogen peroxide vapor, the catalytic deviceconverts the hydrogen peroxide vapor into water and oxygen.

According to the present invention, a plurality of sensors is associatedwith decontamination chamber 30 and aeration chamber 60. The pluralityof sensors is connected to controller 160 (described in detail below) toprovide signals indicative of the operation of system 10.

A temperature sensor 162 and a sterilant vapor sensor 164 are disposedin interior space or region 32 c at a location proximate to conveyor 14.In the embodiment shown, temperature sensor 162 and sterilant vaporsensor 164 are disposed within manifold 134 in housing 32 ofdecontamination chamber 30. Temperature sensor 162 provides a signalindicative of the temperature of the sterilant vapor exiting manifold134. Sterilant vapor sensor 164 provides a signal indicative of theconcentration of sterilant vapor exiting manifold 134. In the embodimentwherein sterilant vapor is hydrogen peroxide vapor, sensor 164 ispreferably a near infrared (IR) sensor.

A temperature sensor 166 is disposed in interior space or region 62 c ata location proximate to conveyor 14. In the embodiment shown,temperature sensor 166 is disposed within manifold 144 in housing 62 ofaeration chamber 60. Temperature sensor 166 provides a signal indicativeof the temperature of the air exiting manifold 144.

A conveyor sensor 168 is disposed relative to conveyor 14. Conveyorsensor 168 provides a signal indicative of the movement of conveyor 14through decontamination chamber 30 and aeration chamber 60. For example,conveyor sensor 168 may provide a signal indicative of the speed atwhich conveyor 14 is moving. It is contemplated that sensor 168 may be aconventionally known sensor, e.g., a proximity sensor, that is usefulfor detecting movement of conveyor 14.

Controller 160 (shown in FIG. 2) may include a microprocessor, memorydevice(s) and a wireless communications interface. An input/output means172 (e.g., an LED or LCD display) is connected to controller 160.Controller 160 is connected to motor 16, actuator 18, heating unit 52and the various components of liquid sterilant supply unit 110, airconditioning unit 120, vaporizer unit 130, aeration unit 140 anddestroyer 150 to allow controller 160 to control the operation thereof.

Controller 160 receives signals from the various sensors associated withsystem 10. In particular, controller 160 receives signals from sensors54, 56, 162, 164, 166, 168 and the various sensors in liquid sterilantsupply unit 110, air conditioning unit 120, vaporizer unit 130, aerationunit 140 and destroyer 150. Controller 160 is programmed to monitorcontinuously the signals from the aforementioned sensors in order tocontrol the operation of system 10, as described below.

Referring now to the operation of the present invention, controller 160is programmed to cause system 10 to operate such that articles 12conveyed along conveyance direction “L” by conveyer 14 aredecontaminated.

Prior to exposing articles 12 to a sterilant vapor, controller 160controls system 10 in a conditioning phase of a decontamination cycle.During the conditioning phase, controller 160 controls system 10 suchthat air conditioning unit 120 conveys clean, dry air along third airsupply line 128. The air then flows along first branch conduit 128 a,second branch conduit 128 b and third branch conduit 128 c. The airexiting first branch conduit 128 a flows in a downward direction betweenspaced-apart entrance walls 36 a, 36 b to branch conduit 154 a connectedto lower wall 46 b. The air flowing between spaced-apart walls 36 a, 36b forms a “curtain of air” to separate inlet end 32 a from thesurrounding environment. As such, the “curtain of air” prevents the airin decontamination chamber 30 from escaping to the surroundingenvironment and prevents the humidity and ambient air from thesurrounding environment from entering decontamination chamber 30.

The air flowing along second branch conduit 128 b from air conditioningunit 120 flows in a downward direction between exit wall 38 of housing32 and entrance wall 66 of housing 62 to branch conduit 154 b connectedto lower wall 82 b. The air flowing between exit wall 38 and entrancewall 66 forms a “curtain of air” that fluidly isolates outlet end 32 bof housing 32 from inlet end 62 a of housing 62.

The air flowing along third branch conduit 128 c from air conditioningunit 120 flows in a downward direction between spaced-apart exit walls68 a, 68 b to branch conduit 154 d connected to lower wall 76 b. The airflowing between spaced-apart exit walls 68 a, 68 b forms a “curtain ofair” to separate outlet end 62 b of housing 60 from the surroundingenvironment. The air flowing into branch conduits 154 a, 154 b and 154 dfrom first branch conduit 128 a, second branch conduit 128 b and thirdbranch conduit 128 c, respectively, is then conveyed to destroyer unit150.

After the aforementioned “curtains of air” are formed, controller 160causes air conditioning unit 120 to convey dry, clean air to vaporizerunit 130 and to aeration unit 140. Controller 160 also causes liquidsterilant supply unit 110 to convey liquid sterilant to vaporizer unit130. Controller 160 controls aeration unit 140 to maintain thetemperature of the air conveyed to manifold 144 in aeration chamber 60to within a predetermined acceptable temperature range, as measured bytemperature sensor 166. Controller 160 controls vaporizer unit 130 tosupply sterilant vapor to manifold 134 in decontamination chamber 30 ata temperature within a predetermined acceptable temperature range, asmeasured by temperature sensor 162, and at a concentration within apredetermined acceptable concentration range, as measure by sterilantvapor sensor 164. According to one embodiment of the present invention,the sterilant vapor is maintained at a concentration between about1.0×10⁻⁹ kg/L and about 0.01 kg/L and at a temperature between about 15°C. and about 90° C. According to another embodiment of the presentinvention, the sterilant vapor is maintained at a concentration betweenabout 7.0×10⁻⁴ kg/L and about 8.5×10⁻³ kg/L.

The air exiting decontamination chamber 30 and aeration chamber 60 flowsalong exhaust conduit 152 and third branch conduit 154 c, respectively,to destroyer unit 150. The sterilant vapor conveyed to destroyer unit150 is destroyed and then exhausted into the surrounding environmentthrough outlet conduit 156.

Controller 160 controls air conditioning unit 120 and destroyer unit 150such that interior space or region 32 c of housing 32 is maintained at anegative pressure. The negative pressure is selected to reduce the riskthat harmful pathogens may escape from decontamination chamber 30 duringthe decontamination process. It is also contemplated that controller 160may control air conditioning unit 120 and destroyer unit 150 such thatinterior space or region 32 c of housing 32 is maintained at atmosphericpressure.

Once the temperature and concentration of sterilant vapor in manifold134 and the temperature of air in manifold 144 are in the aforementionedpredetermined acceptable ranges, controller 160 ceases the conditioningphase. Controller 160 then controls system 10 during a decontaminationphase. During the decontamination phase, controller 160 energizes motor16 to cause conveyor 14 to convey articles 12 through decontaminationchamber 30 and through aeration chamber 60. After articles 12 passthrough the curtain of air formed between spaced-apart entrance walls 36a, 36 b, first temperature sensor 54 measures the temperature ofarticles 12. If the temperature of articles 12 is below a lower limit ofa predetermined temperature range, controller 160 energizes heating unit52 to heat articles 12 to a temperature that is within the predeterminedtemperature range. Second temperature sensor 56 measures the temperatureof articles 12 after heating unit 52 to determine whether articles 12have been heated to a temperature within the predetermined temperaturerange.

Controller 160 is programmed to adjust the power supplied to heatingunit 52 and the speed of conveyor 14 to heat articles 12 to within theaforementioned predetermined temperature range. In this respect,controller 160 is programmed to increase the speed of conveyor 14 and/ordecrease the power supplied to heating unit 52 if articles 12 are heatedto a temperature that exceeds an upper limit of the aforementionedpredetermined temperature range. Similarly, controller 160 is programmedto reduce the speed of conveyor 14 and/or increase the power supplied toheating unit 52 if articles 12 are not heated to a temperature thatexceeds the lower limit of the aforementioned predetermined temperaturerange.

As can be appreciated, it may be necessary for system 10 to conveyseveral articles 12 through decontamination chamber 30 until a steadystate condition is reached wherein articles 12 are heated to atemperature within the predetermined temperature range. Articles 12 thatare not heated to a temperature within the predetermined temperaturerange are discarded or returned to be reprocessed in system 10.

It is contemplated that the upper limit of the predetermined temperaturerange for articles 12 is about 90° C. In the embodiment of the presentinvention wherein articles 12 are eggs, controller 160 controls heatingunit 52 to heat articles 12 to a temperature that is below about 60° C.The foregoing upper limit is selected to prevent the eggs from cookingor from causing other deleterious effects (e.g., coagulation).

It is also contemplated that the lower limit of the predeterminedtemperature range for articles 12 is a temperature that is greater thanthe temperature of the sterilant vapor exiting manifold 134. As such,the sterilant vapor exiting manifold 134 is prevented from condensing onarticles 12. In the embodiment wherein articles 12 are eggs,condensation of sterilant on articles 12 increases the likelihood thatsterilant may penetrate through the porous outer surface of the eggs.Due to the difficulty involved in removing sterilant that has penetratedthrough the outer surface of an egg and the harmful effects thesterilant may have on humans, it is desirable to prevent the sterilantfrom condensing on the eggs.

As articles 12 pass over manifold 134, actuator 18 repeatedly engagesconveyor 14 such that articles 12 disposed thereon move slightly. Theslight movement of articles 12 is designed to prevent any one portion ofarticle 12 from remaining in contact with conveyor 14 during the entiredecontamination phase. The slight movement of articles 12 allows acontact point between article 12 and conveyor 14 to change, therebyexposing the entire surfaces of articles 12 to the sterilant vapor.

It is also contemplated that the flow rate of air from manifold 134 maybe selected such that articles 12 are slightly suspended above conveyor14 on a “cushion of air.” As such, no portion of articles 12 contactsconveyor 14 while being exposed to the sterilant vapor, thereby exposingthe entire outer surfaces of articles 12 to the sterilant vapor.

Controller 160 also controls motor 16 such that the speed of conveyor12, as measured by conveyor sensor 168, causes articles 12 to bedisposed in decontamination chamber 30 for a predetermined period oftime. The predetermined period of time is selected by the user to ensurethat articles 12 are decontaminated while not allowing the sterilantvapor to penetrate through outer surfaces of articles 12. In theembodiment wherein articles 12 are eggs, the predetermined period oftime is less than about thirty (30) seconds such that the sterilantvapor does not penetrate through the shell of the egg. The predeterminedperiod of time and the predetermined concentration of sterilant vaporare selected to provide a 5 log reduction of pathogens, such assalmonella.

Conveyor 14 then transports articles 12 through the curtain of airdisposed between decontamination chamber 30 and aeration chamber 60 andinto interior space or region 62 c of housing 62. Once in interior spaceor region 62 c, articles 12 are exposed to a dry, clean air exitingmanifold 144. The dry, clean air removes the sterilant vapor fromarticles 12. The air and the removed sterilant vapor exit interior spaceor region 62 c through outlet port 64 along branch conduit 154 c and areconveyed to destroyer 150.

It is contemplated that aeration chamber 60 may be connected to a sourceof a neutralizing agent. In the embodiment wherein the sterilant vaporis hydrogen peroxide vapor, the neutralizing agent neutralizes thehydrogen peroxide vapor on articles 12 so that articles 12 are safe forhuman consumption. The neutralizing agent may include sodiumthiosulfate, sodium methyl sulfate, sodium metabisulfite or otherreducing agents.

After articles 12 have remained in aeration chamber 60 for auser-defined period of time, conveyor 14 conveys articles 12 through thecurtain of air formed between spaced-apart exit walls 68 a, 68 b.Articles 12 then exit system 10 for further processing, if desired.

The present invention, thus, provides a method and a system fordecontaminating food articles having a porous outer surface. Inparticular, the present invention conveys the food articles through adecontamination chamber at a predetermined speed and exposes the foodarticles to a sterilant vapor having a predetermined concentration. Thepresent invention exposes the food articles to the sterilant vapor for apredetermined period of time that is selected to prevent the sterilantvapor from penetrating the outer porous surfaces of the food articles.Moreover, the present invention causes the food articles to remain inmotion or to be suspended above a conveyor during a decontaminationphase such that the entire outer surfaces of the food articles areexposed to the sterilant vapor. Further still, the temperature of thesterilant vapor is selected to decontaminate the food articles while notcausing undesirable side effects (e.g., partial cooking) to the foodarticles. In one embodiment of the present invention, the food articlesare heated to a temperature that prevents the sterilant vapor fromcondensing on the porous outer surfaces of the food articles.

Methods and systems known heretofore tend to over-expose food articlesto a sterilant vapor or overheat the food articles, thereby causingundesirable side effects, such as partially cooked food articles, orpenetration of the sterilant vapor into the food articles. The presentinvention overcomes the foregoing problems and allows for efficient andquick decontamination of food articles, as compared to systems knownheretofore.

The foregoing description is a specific embodiment of the presentinvention. It should be appreciated that this embodiment is describedfor purposes of illustration only, and that numerous alterations andmodifications may be practiced by those skilled in the art withoutdeparting from the spirit and scope of the invention. It is intendedthat all such modifications and alterations be included insofar as theycome within the scope of the invention as claimed or the equivalentsthereof.

Having described the invention, the following is claimed:
 1. A systemfor decontaminating articles having porous outer surfaces, said systemcomprised of: a decontamination chamber; a conveyor for conveying saidarticles through said decontamination chamber; a source of sterilantvapor; conveying means for conveying a sterilant vapor from said sourceof sterilant vapor to said decontamination chamber; a controller forcontrolling said conveyor and said source of sterilant vapor, saidcontroller programmed to: control said source of sterilant vapor tomaintain said sterilant vapor within a predetermined acceptableconcentration range and within a predetermined acceptable temperaturerange; and control said conveyor to convey said articles through saiddecontamination chamber at a predetermined speed wherein saidpredetermined speed is selected such that said articles are disposed insaid decontamination chamber for a predetermined period of time; andheating means for heating said articles wherein said controller isprogrammed to control said heating means to maintain said articles at atemperature greater than the temperature of said sterilant vapor andless than a maximum acceptable temperature of said articles, whereinsaid predetermined period of time and said predetermined acceptableconcentration range of said sterilant vapor are selected such that saidsterilant vapor does not penetrate said porous outer surfaces of saidarticles.
 2. A system as defined in claim 1, wherein said articles areeggs.
 3. A system as defined in claim 1, wherein said system furthercomprises: a first pair of spaced-apart walls disposed at an entranceend of said decontamination chamber; wherein a space defined betweensaid spaced-apart walls defines a flow path for conveying pressurizedair therealong, said pressurized air forming a curtain of air forseparating an interior space of said decontamination chamber from asurrounding environment.
 4. A system as defined in claim 1, wherein saidconveyor includes a meshed surface.
 5. A system as defined in claim 1,wherein said system further comprises: a manifold connected to saidsource of sterilant vapor, said manifold disposed below said conveyorfor conveying said sterilant vapor in a generally upward direction oversaid articles disposed on said conveyor.
 6. A system as defined in claim1, wherein said sterilant vapor includes one or more of the following:hydrogen peroxide, ozone and peracetic acid.
 7. A system fordecontaminating articles having porous outer surfaces, said systemcomprised of: a decontamination chamber; a conveyor for conveying saidarticles through said decontamination chamber; a source of sterilantvapor; conveying means for conveying a sterilant vapor from said sourceof sterilant vapor to said decontamination chamber; a controller forcontrolling said conveyor and said source of sterilant vapor, saidcontroller programmed to: control said source of sterilant vapor tomaintain said sterilant vapor within a predetermined acceptableconcentration range and within a predetermined acceptable temperaturerange; and control said conveyor to convey said articles through saiddecontamination chamber at a predetermined speed wherein saidpredetermined speed is selected such that said articles are disposed insaid decontamination chamber for a predetermined period of time; and anactuator disposed in said decontamination chamber, said actuatorpositioned to engaged said conveyor to cause movement of said articlesrelative to said conveyor as said articles are conveyed through saiddecontamination chamber, wherein said predetermined period of time andsaid predetermined acceptable concentration range of said sterilantvapor are selected such that said sterilant vapor does not penetratesaid porous outer surfaces of said articles.